Symantec Desktop Encryption always encrypts email

I am using Symantec Desktop Encryption 10.3.0. Every time I send an email to someone whose key is in my keyring the email is automatically encrypted.

I am using Outlook 2013 with POP servers.

I have configured Symantec Desktop Encryption via Options->Messaging-> secure e-mail and have set " activate PGP-encryption Button ... in Outlook".
But it does not matter, if I set the "Encryption" button when creating a new email, or not, the emails are always encrypted. The only policies I have in place are Sign & Encrypt, Sign Button, and Encrypt Button.

How can I choose the emails I wish to encrypt and the rest which I do not want encrypted?

Thanks in advance.